In the year 1930 Mr P. WAGENAAR HUMMELINCK, Utrecht, made a trip to the Netherlands West Indian Islands of Curaçao, Bonaire and Aruba with the intention of collecting zoological objects and of gathering data of zoogeographical interest (see lit. 8). In the years 1936—37 he again collected in these islands and, moreover, visited the islands of Margarita and Los Testigos off the coast of Venezuela, the Venezuelan peninsula Paraguaná and the Colombian peninsula La Goajira. To get a better impression of ecological circumstances in pools and puddles of which a zoological inventory was made, he also gathered Algae and floating and submerged Phanerogams occurring in the collecting stations. On the collector’s request the present author made a study of the aquatic Phanerogams, which gave rise to some critical notes. As, moreover, several new localities were discovered and a series of ecological particulars were given by the collector, a complete enumeration of the collected specimens may follow. The specimens were preserved in small collecting bottles in alcohol and in formaline and are now inserted both in the Rijksherbarium at Leiden and in the University Herbarium at Utrecht.